The use of weatherstripping between moving and stationary members, such as doors and windows and their surrounding frames, is well known. The functions of such weatherstripping is to reduce draughts and ingress of air, impede ingress of rain and water, and to reduce noise due to any movement of a door or window caused by wind or a source of vibration. Weatherstripping having one or more rows of upstanding pile fiber of resilient filaments is commonly employed, and such pile weatherstripping may have a barrier fin. The function of the barrier fin is to increase the imperviousness of the weatherstripping to penetration of water and air therethrough.
Disclosed in U.S. Pat. No. 3,175,256 (Horton) is a central barrier fin formed by a sheet of flexible plastic material disposed between two rows of pile fiber. In some embodiments the two spaced apart pile rows are formed on a base strip first, and then a strip of the flexible plastic material is separately inserted between the two pile rows and stuck to the base strip. In other embodiments, the barrier fin is formed first integrally with the base strip, then a row of pile fiber attached to the backing strip on each side of the barrier fin by a flocking process or by attaching strips of woven pile.
U.S. Pat. No. 3,745,053 (Johnson et al) discloses another weatherstripping product having a central barrier fin between two rows of pile fiber. The pile fiber rows are first formed on a backing strip, then an unfolded or folded strip inserted between the pile rows and adhesively attached directly to the pile fiber to form a barrier fin.
U.S. Pat. No. 3,404,487 (Johnson et al) discloses a different approach to forming a barrier fin. After attaching a body of upstanding flexible and resilient fibers to a backing strip, a coating in the form of a plastisol is applied to one or both sides of the body of upstanding fibers. The coating spans the space between adjacent fibers and between these fibers and the backing strip, and when cured forms a continuous outer film. The resultant weatherstripping product has a barrier fin along one or both sides of the central body of fibers, the fin or fins being adhered to both the outside fibers and the backing strip.
One of the problems with separately attached or adhered barrier fins, as disclosed in the above U.S. patents, is that during the wear and tear that weatherstripping can be subjected to during use between two closely fitting and relatively movable members, e.g. a door and its frame, and at times also during insertion of the weatherstripping into its retaining slot in one of such members, the barrier fin can become torn from the weatherstripping. The risk of this occurring is increased at any location where there is a defect in the adherence of the barrier fin to the weatherstripping.
To avoid the separate step involved in attaching a barrier fin, it is proposed in U.S. Pat. No. 4,352,845 (Miska) to form pile weatherstripping with one or more rows of the pile being formed from monofilament yarns having an X-shaped cross-section. These X cross-sectioned monofilaments are intended to nest or intermesh together to reduce the infiltration of air and moisture through the pile of the weatherstripping. Although this proposal eliminates the need to separately secure a barrier fin, the intermeshing X-shaped cross-section monofilaments do not form a continuous, impermeable barrier wall to substantially eliminate the passage of draughts and water therethrough.
Another proposal to eliminate the step of separately attaching a barrier fin is disclosed in U.S. Pat. No. 4,164,599 (Kessler). This proposes forming an elongate windbreak in pile weatherstripping by having in the pile a row of individual fibers which are bonded together. The fibers to be so bonded are formed from a different material than the fibers which are not bonded, and/or are coated with a bonding agent, such as a water emulsion of ethylene vinyl acetate, to which is preferably added a mixture of materials susceptible to heating by radio frequency or other electromagnetic energy. Such a "susceptor" which is responsive to an alternating magnetic field is given as gamma Fe.sub.2 0.sub.3. After the weatherstripping blank has been fabricated, the whole blank is passed through a radio frequency energy generator which heats the coated fibers and causes them to adhere together while the remaining fibers remain unbonded. It is proposed in this way to form a multiplicity of generally parallel coated fibers which are bonded together to form a windbreak, which acts to support the unbonded fibers in use and acts in some measure to mitigate air and water passing through the weatherstripping. It is stated that this windbreak need not be impermeable or imperforate. As can be seen from the drawings in this U.S. Patent, many spaces still remain between the bonded fibers which will thus permit some penetration of draughts and rain. Further, it is particularly noted that the unbonded fibers should be selected so as to have no external adhesiveness when subjected to an application of such energy, and examples of such unbondable synthetic fibers are given as polyethylene and polypropylene. Examples of bondable fibers are given as nylon and polyvinylchloride.
The above proposals of Miska and Kessler, although eliminating separately attaching a barrier fin, do not provide weatherstripping having a barrier fin which is impervious to the penetration of air and water. Further, is is observed that as polypropylene and polyethylene have a lower melting point than nylon, such differential bonding of the fiber as suggested in Kessler could not be effected by directly applying heat.